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United States Patent | 6,094,592 |
Yorkey ,   et al. | July 25, 2000 |
A method for use in a system for determining a physiological parameter is described. The system has a sensor for transmitting electromagnetic energy of first and second wavelengths toward a tissue sample and detecting the electromagnetic energy after scattering of the electromagnetic energy by the tissue sample, thereby generating a first signal corresponding to the first wavelength and a second signal corresponding to the second wavelength. The first and second signals are transformed into the frequency domain, thereby generating third and fourth signals. A ratio signal is generated using the third and fourth signals. For each of a plurality of ratio values an associated sum is generated corresponding to the number of times the ratio signal coincides with the ratio value associated with the sum. Contributions to each sum are weighted in accordance with the third signal. A best ratio value is selected from the plurality of ratio values based on the sums associated therewith.
Inventors: | Yorkey; Thomas J. (San Ramon, CA); Mannheimer; Paul D. (Danville, CA) |
Assignee: | Nellcor Puritan Bennett, Inc. (Pleasanton, CA) |
Appl. No.: | 085475 |
Filed: | May 26, 1998 |
Current U.S. Class: | 600/475; 600/310 |
Intern'l Class: | A61B 005/00 |
Field of Search: | 600/407,310,322,323,473,475,476 356/41 |
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